1. Earpiece color, black vs white
2. Side finish, matte vs glossy
3. Back finish, soft-touch vs regular matte plastic (contrary to what Engadget reported)
I was going to grab the white one for the look, but after getting them in my hands, I changed my mind. That soft touch back on the black one is really comfortable to touch (I don't plan on using a case anyway). Also, I prefer the earpiece to be black.
Also take a look at this post: